I'm having an awful time on O2 this past few weeks.
Intermittently, when I make/receive calls the person at the other end of the line cannot hear me. The call connects ok, I can hear them perfectly but they can't hear me. It happens on speakerphone & car kit too. I've tested all three scenarios on Skype & Viber and no such problems which has me thinking it could be a network issue.
Eventually I ordered an replacement from Apple under warranty which I got last Monday, and now just yesterday the same problem has occurred on this new one too!
Any ideas? I've restored it to factory settings, and it's on the latest OS, but the problem started before I upgraded the first one too.